Vacuum operated counterbalance



June 13, 1944. c. R. BUCHET 2,351,397

VACUUM OPERATED COUNTER BALANCE I Filed Aug. 29, 1941 2 Sheets-Sheet 1 INVENTOR.

c. R. BUCHET June 13, 1944. c. BUCHET 2,351,397

VACUUM OPERATED COUNTER BALANCE Filed Aug. 29, 1941 2 Sheets-Sheet 2 Q INVENTOR.

Patented June 13, 1944 VACUUM OPERATED OOUNTERBALANCE Conrad R. Buchet, Los Angeles, Calif., assignor of one-third to Darrell Marsden Dowding and one-third to John Cummings Tyler, both of Los Angeles, Calif.

Application August 29, 1941, Serial No. 408,781

3 Claims. (01. 2671) This invention relates to a vacuum operated counter-balance.

The general object of the invention is to provide an improved counter-balance adapted for use with moving members and wherein the counter-balance includes a, piston which is controlled by a partial vacuum in the piston cylinder.

A more specific object of the invention is to provide a counter-balance particularly adapted for use with a pump jack wherein a cylinder and piston are employed and wherein the piston is connected to the walking beam and is subject to a vacuum on one face thereof during a portion of its movement.

Another object of the invention is to provide a pump jack including a plurality of piston members mounted in a single elongated cylindrical member.

Another object of the invention is to provide a novel means for lubricating the piston of a pump jack counter-balance.

Other objects and advantages of my invention will be apparent from the following description taken in connection with the accompanying drawings, wherein:

Fig. 1 is a side elevation partly in section showing my invention.

Fig. 2 is a fragmentary section sectional view with parts in elevation showing the counter-balancing cylinder.

Fig. 3 is a fragmentary enlarged sectional detail.

Fig. 4 is a fragmentary elevational view partly in section showing a modification, and

Fig. 5 is an elevation partly in section showing a further modification.

Referring to the drawings by reference characters, I have shown my invention as embodied in a pump jack which is indicated generally at l9. As shown, the pump jack includes a base or support H on which a column I2 is mounted. This column l2 pivotally supports a walking beam I3 which serves to move a sucker rod l4 up and down as the walking beam is reciprocated through movement of a link l5 which is connected to a crank member l6 which may be operated in any desired manner. The construction of the walking beam and associated parts form no part of the present invention which relates to a counter-balance as indicated generally at I! as including a cylindrical member l8. The cylindrical member l8 includes an upper cylinder l9 and a lower cylinder 29 which are inserted in and secured to a coupling member 2| which has an end 22 forming a partition between the cylindrical members l9 and 29.

At its upper end the cylinder is provided with a closure 22' which has a packing gland 23 therein through which a piston rod 24 extends. The lower cylinder member 29 is closed by an end member 25 which includes a boss 26. The boss 26 is pivoted as at 21 to a slide member 28 mounted on a sliding block 29 which slides along the base IL A hand wheel 39 is connected to a screw 3| which is threaded into the block 29 so that as the hand wheel is rotated the block 29 will be shifted back and forth depending on the direction of the rotation of the hand wheel.

The upper end of the piston rod 24 is pivoted as at 32 in one of a group of apertures 33 in the walking beam l3. The piston rod 24 includes a pair of pistons 34 and 35 with the upper piston 34 disposed in the cylindrical portion l9 and the lower piston disposed in the cylindrical portion 29.

The piston rod 24 is continuous throughout the cylinder and is suitably connected to the pistons. Each of the cylindrical portions l9 and 29 is provided with ableed hole 36 which preferably is open at all times to the atmosphere so that the air will not be compressed in the upper portion of the cylinder as the piston reciprocates.

In the lower portion of each cylinder I provide a passage 31 which at its outer end is normally closed by a ball valve 31'. The ball valve is normally urged to its seat by a spring 38 which is held in place by a closure plug 39. The construction of the valve is such that as the pistons move downwardly air will be forced through the passage 31 as soon as the air pressure in the cylinder exceeds atmospheric pressure. When the pistons, however, are moving upwardly, the ball valves 31" being seated will prevent entry of air into the cylinders so that a partial vacuum will be formed in the lower end of each cylinder as soon as the pistons start their upward movement.

In order to provide lubrication for the pistons I provide each cylindrical portion l9 and 29 with a conduit 49. The upper end 4| of each conduit communicates with its associated cylinder above the top most position assumed by the piston and communicates at 42 with its associated cylindrical portion at the bottom of the cylinder. the piston, when the piston is in its lower most position, is less than the volume of the asso- The volume in each cylinder below ciated conduit 40 so that each time the piston moves downwardly it forces lubricating material through the conduit 40 whence it is discharged on the top of the piston. As the lubricating material seeps by the piston it is forced back on the top of the piston to keep the latter lubricated. As a lubricating material I preferably employ a mixture of mineral oil and mercury.

In the lower end of the cylindrical portion 20 I preferably arrange a plate 43 which has a notch 44 therein adjacent to the conduit 48. The notch 44 serves as a sump to receive oil when the piston moves to its extreme low position. The plate 43 alsoincludes a'recess 45 through which a headed member 46 extends. This member 46 serves as a tell-tale and is nor mally urged upwardly by a. spring 41. The member 46 passes through a packing gland 48. Each time the piston descends the tell-tale is moved so that the downward limit of movementof the piston can be determined. A pin 46 .on the member 46 limits .the upward movement of this member.

In Fig. 4, I: show a modification of my invention wherein the construction is similar to that previously described and wherein like parts are designated by similarly primed reference numerals. In this modification I employ only the lower cylinder member 20.

In Fig. 5 I show a modification ofmy invention wherein a pairof the cylinder members are arranged in side-by-side relation. Inthis further modification similar partsare designated by similarly double primed reference numerals. In this further modification the piston rods 24 are connected to a yoke 49 which has ears 5!! adapted to be connected to the walking beam. In this further modification the lowerclosure members 25" are connected byacoupling member 5| with the sliding block 29.

In the three types the conduits 40, 40 and 40" are each provided with .a one'way ball valve 52. Oil passing up through the pipes 40-, 40' and 40" readily passesthis ball valve while the ball valve prevents downward movement of air through the respective pipes.

In all of the types the vacuum controlled piston counter-balance the weight of the sucker rod as the latter moves downwardly in the well and when the sucker rod starts its upper movement,the partial vacuum acting upon-the piston tends to assist in pulling the sucker rod upwardly. I

From the foregoing description it will be apparent that I have invented a novel counterbalance which can be economically manufactured and is highly efiicient for the intended purpose.

Having thus described my invention, I claim: 1. In a counterbalance for a walking beam member, a support member, a cylinder, means to pivotally attach the cylinder to one of the members, a piston in the cylinder, said piston including a rod, means to pivotally attach the piston rod to the other member, means to shift the piston rod attaching means along the member to which it is attached, means to at all times bleed one end portion of the cylinder to the atmosphere, said cylinder having a passage in the other end portion thereof extending to the atmosphere, and valve means forcontrolling communication through said passage to the atmosphere, said valve means including a valve member movable to normally prevent passage of air into the cylinder but permitting ready passage of air from the cylinder, a conduit having one end opening into the cylinder adjacent the lower end thereof, said conduit also opening into the cylinderadjacent the upper end thereof, the volume in the cylinder below the piston when the piston is in its extreme down position being less than the volume of the conduit, and a mixture of oil and mercury in the cylinder. v

2. In a counterbalance for a walkingbeam member, a support member, a cylinder, means to pivotally attach the cylinder to one of 'the members, a partition in the cylinder, a pair of pistons in the cylinder, one at each side of the partition, said pistons being spaced apart, a piston rod connecting said pistonsymea ns to pivotally attach the piston rod to the other member, means in the wall of the cylinder to at all times bleed the portions of the cylinder above each piston to the atmosphere, said cylinder having passages in the wall thereof below the pistons and extending to the atmosphere, and valve means for controlling communication through said passage -to "the atmosphere, said valve means including a valve member movable to-normally prevent passage of air into the cylinder but permitting ready passage of air from the cylinder, and a pair of conduits each 'having one end opening into the cylinder adjacent the lower end location occupied by each piston when in lowered position, each conduit also opening into the cylinder above the associated piston, the volume in the cylinder below each piston when the pistons are in their extreme down position being less than the volume of the conduit. 7 1

3. In a counterbalancing: device for a movable member, a cylinder, a single partition in the cylinder and spaced from the ends thereof, a, piston on each side of the partition,'a piston rod-connecting said pistons, means in the wall of the cylinder to at all times bleed the portion of the cylinder above each piston to the atmosphere, said cylinder having a passage therein in the wall thereof below each piston and extending to the atmosphere, and valve means for controlling communication through each passage to the atmosphere, each valve means including a valve member movable to normally prevent passage of air into the cylinder but permitting ready passage of air from the cylinder.

CONRAD R. BUCHET. 

